Jaume Balagueró is probably best known in these parts as one half of the team behind the extraordinarily popular [REC] franchise (with Paco Plaza) and for his trio of supernatural spookfests, Fragile, Darkness, and the excellent The Nameless. With Sleep Tight (Mientras duermes), Balagueró trades in his signature demons and ghosts for a very different but no less terrifying monster.

When we are first introduced to Cesar (Luis Tosar), he is standing on the rooftop ledge of an apartment building, staring down into the dark and empty streets, contemplating his own demise. He’s an immensely unhappy man who, despite his best efforts, can’t shake the feelings of hopelessness and despair that torment his very being. We then cut to Cesar lying in bed beside a gorgeous young woman. Cesar quietly slips out of bed, gathers his things, and goes through the motions of preparing for another day.

Cesar arrives to his post as concierge of an upscale apartment building, where he dutifully greets each resident as they, too, begin their day. He hands them newspapers, offers compliments and bits of small talk, and does all of the little things that make the people who live in his building feel like they’re getting their money’s worth. At first glance, Cesar seems like a pleasingly acquiescent and good-natured fellow. That is, until Clara (Marta Artura), the woman with whom Cesar awoke, emerges from the elevator.

Clara greets Cesar warmly, but it’s obvious that, at least to her knowledge, their relationship begins and ends with their awkward exchanges in the building’s lobby. As Clara rushes off, Cesar is then confronted by Ursula (Iris Almeida), the precocious pre-teen daughter of a tenant, who proceeds to shake him down for sixty Euros before spitting a mouthful of chocolate milk on his desk. She knows something about Cesar; something so vile that Cesar is willing to pay anything to buy her silence.

Later that night, Cesar sneaks into Clara’s apartment, whereupon he slips under her bed and awaits her return home. Once Clara sets down for the night, Cesar gets to work, producing a kit of chloroform he keeps stashed inside her box-spring, and anesthetizing her so that he may do his bidding. He explores her apartment, destroys/hides her belongings, tampers with her make-up and soaps, uses her toothbrush, and then lies down beside her until just before dawn, when he beats a hasty retreat, hopeful that his night’s work will have its desired effect.

Clara, meanwhile, awakens each morning feeling worse than the one prior, despite, what she thinks, is a night of restful sleep. Regardless, she arrives in the lobby each morning with a smile and a positive outlook. For Cesar, this will not do, for, you see, he is schadenfreude incarnate; a man who quite literally lives to make others miserable. Despite his best efforts, however, the joyful Clara simply will not break, forcing a desperate Cesar to take things to new extremes.

Watching Sleep Tight, I couldn’t help but be reminded of 2011’s Hammer offering, The Resident, which also revolved around a depraved man’s nocturnal visitations upon a drugged, helpless victim. However, The Resident was, at its core, a story of unrequited love. Sleep Tight is an entirely different animal altogether. Cesar doesn’t love Clara for he has no love to give. He simply wants to destroy her; to force her to share in his misery. And she’s not his only target; she’s just the one that’s proven to be the greatest challenge, and, as such, requires more of his attention and “motivation”. It’s the character of Cesar, both as written and as portrayed by the mesmerizing Tosar, that makes Sleep Tight such a satisfying and deliciously deviant viewing experience. The bushy-browed actor’s mannerisms, tics, and delivery convey a disarming sense of sadness and vulnerability, but, at the same time, barely mask the evil and rage that threaten to crack Cesar’s gentle façade. It’s a credit to Tosar’s performance that I couldn’t help but find myself sort of rooting for Cesar despite the fact that, at his core, he’s one of the most despicable screen villains I’ve seen.

For the first two thirds of the film, Sleep Tight is a quiet, deliberately paced affair, but, when the stakes are raised in the film’s third act, the director unleashes his inner-Hitchcock, dishing out healthy doses of white knuckle inducing suspense as Cesar’s world comes crashing down all around him (or does it?). It’s a decidedly different style of film from Balagueró who, in his previous outings, employed claustrophobic atmosphere and jump shocks to scare us. Sleep Tight elicits chills of a much more visceral nature, resulting in Balaguerós most accomplished and mature film to date.

Sleep Tight comes to Blu-ray courtesy of Dark Sky Films, and is presented in a 2.35:1 transfer that is crisp and clean for the most part, offering a subdued yet pleasing color palette, and impressive definition and facial detail. Blacks, however, are problematic, as they’re inconsistent throughout, often appearing washed out, and, on occasion, teeming with what appears to be digital noise. I found this most evident in the sequences in which Cesar hides out beneath Clara’s bed, where facial detail and shadow is all but obscured by vaguely flickering colored pixels and harsh edges. It’s not anything that’d put me off watching the film, but I’d be remiss if I didn’t at least report my findings to potential buyers. Otherwise, the image looks pretty damned good, and the accompanying DTS HD 5.1 Master Audio soundtrack (in Spanish w/ English Subtitles) compliments this with a deceptively quiet, very well-mixed track that features smartly implemented subtle directional cues and nicely isolated sound effects that make for a crisp, organic listening experience.

There aren’t a lot of extras but, boy howdy, they sure packed a lot into one of them. I’m talking about the behind-the-scenes feature Cesar’s World (SD – Spanish w/ English Subs), which clocks in at an hour and 47 minutes! That’s 45 minutes longer than the film, itself! This exhaustive collection of raw footage and interviews answers just about every question a viewer could have about the film and then some, and, despite its length, it’s a remarkably fast-moving and entertaining! Dark Sky also rounds out a collection of deleted scenes (SD) and trailer’s for this film and other Dark Sky releases (HD).